"He's awful tough to defend," Fangio said Tuesday. "After watching a lot of film of him in the offseason knowing our first game was against him, he reminds me of Dan Marino in the pocket with his quick, accurate release.

"He reminds me of Steve Young out of the pocket. That's a hell of combination to defend. We have to do a good job in our run lanes and we have to do a good job plastering guys in coverage."

In the 49ers' season-opening win at Green Bay, Rodgers completed 30 of 44 passes for 303 yards with two touchdowns and a key fourth-quarter interception by NaVorro Bowman.

Kickoff is at 5 p.m. for the No. 2-seed 49ers (11-4-1) opener against the No. 3-seed Packers (12-5) in Saturday's divisional-round playoff game at Candlestick Park.

If Smith is struggling in his comeback, however, Fangio won't hesitate to pull him.

"From my point of view, if someone is not playing up to his standard or close to it, we'll put the next guy in," Fangio added. "In my experience, somebody at 80 percent is not as good as the next guy at 100 percent."